Problem: Khan.scratchpad.disable(); To move up to the maestro level in her piano school, Stephanie needs to master at least $138$ songs. Stephanie has already mastered $25$ songs. If Stephanie can master $10$ songs per month, what is the minimum number of months it will take her to move to the maestro level?
Explanation: To solve this, let's set up an expression to show how many songs Stephanie will have mastered after each month. Number of songs mastered $=$ $ $ Months at school $\times$ Songs mastered per month $+$ Songs already mastered Since Stephanie Needs to have at least $138$ songs mastered to move to maestro level, we can set up an inequality to find the number of months needed. Number of songs mastered $\geq 138$ Months at school $\times$ Songs mastered per month $ +$ Songs already mastered $\geq 138$ We are solving for the months spent at school, so let the number of months be represented by the variable $x$ We can now plug in: $x \cdot 10 + 25 \geq 138$ $ x \cdot 10 \geq 138 - 25 $ $ x \cdot 10 \geq 113 $ $x \geq \dfrac{113}{10} \approx 11.30$ Since we only care about whole months that Stephanie has spent working, we round $11.30$ up to $12$ Stephanie must work for at least 12 months.